They are NLA as well. I’ve been looking at the later model Nissans that have a similar body but a different plug… but ultimately decided to do some more investigation on the root cause first.

im guessing what clay is saying is there is info on a modern sub or alternative for the Nissan (Datsun) that is still floating around. unlike trying to find info on a sub for a 914/924/944?

i know down here the smart 911 mechanics have figured out the coolant temp sensor for a certain model holden (GM) commodore is the same as the head temp sensor on certain 911s. .....and can be screwed straight in to do the job. and you guessed it, its cheaper (of course).


EDIT

here is an ebay ad of interest maybe?


its a rebuild kit for AAV. not strictly right one, for VW Golf 1 etc. german by the looks of it. but i'm betting its so close its not funny when it comes to these things. ie 924.
how far is that from a golf passat engine of same era. or a 914.


https://www.ebay.com/itm/185166067358?_trkp...7Cclp%3A2047675

Just an FYI.... the CHT for a 914 is NLA. The aftermarket ones are problematic and fail randomly.

But you can use a CHT from a 911 Carrera. It will screw in the head, and has the correct curve when warming up. But you have to change the harness to get it to plug in. Just use an L-Jet injector connector. Hook one side to the existing CHT wire, and hook the other side to ground. The Carrera sensor does not ground through the head.

Clay

thanks again. might need that at christmas time.

Good thing I have a spare or two. Almost everything electronic aftermarket is problematic it seems.

My 2.3 build won't idle until head temp gets to 250 then all is good.
An AFM spring compromise to use the L Jet

Hmmmmm

This is interesting, an adjustment on the AAR? Never knew that. The 2056 probably would like more air to keep the AFM flap open to feed more fuel during cold start conditions…



Kinda what my foot does at that time

Gives me some hope…

Alright, I’m back home today and this morning it was a chilly 4C. So, I was able to give it a proper cold start and do my little test.

First, I started the car as normal and then jumped out and pinched the short line from the AAR to the manifold. To my surprise I only got a subtle 100-ish RPM drop. I unclamped and reclaimed just to be sure, but yeah, that’s all I got.
Also, the car started no different today at 4C than it does at 15C. I thought that was interesting too.

Second, just for S’s and G’s I pulled the line from the boot to the AAR and the car died instantly. And I mean the instant I disconnected that hose. I had no time to even put my thumb over the ends. So, as predicted that is a lost cause.

Lastly, I moved the adjustment pin on the AAR all the way to the outside but got no change. I didn’t expect much really given how cold it is. I’m pretty sure the AAR is as open as it can be.

My thoughts so far:
I’m confident that everything is in fact functioning, but if I want to get the idle higher, I’m going to need more air flowing through the AAR channel during warm up.
Which means, I’m at a dead end for now.

Van

Very interesting! I am glad it dropped. That means you are rich and that is easier to deal with (I think). I would get one of those aars the guys were talking about. I doubt they are expensive. I suspect yours isn't opening enough.

On my 2.0, when I cut the aar off at cold start the idle drops 300 rpm, as the car warms the differential gets more and more. So after a few minutes of warm up it will be at 1400 rpm, and will drop to 800 when I close the valve.

Yeah, I don’t know what they are talking about. The 280SX AARs are NLA as well and the ones you can get as NOS are just as much as the VW part. I’m not quite to the point that I’d be willing to spend money on a rebuild.

Now what would be cool is if I can devise a way to get a secondary air injection pump in the loop so that the AFM can still determine proper fueling… but that’s just me dreaming right now…

@Van B
yes to the datsun stuff being just as expensive.
i think i know of a datsun bloke i can ask about this though and maybe there is a substitute that is around that some folks know about. otherwise, mine is just going to get another clean!

can i ask a favour. we are researching some stuff on the history of all the vac tube set ups between dist and throttle body for 1.8s.

can you take a photo of your emission sticker thats in the engine bay?
give us a Vin date. month and year.

and take a photo of your throttle body and distributor showing the vacuum line hook ups for advance and retard. post them up here. if you got time.

Maybe that's an idea too. I think you said you checked to see if it was functioning on the bench but did you check to see if it was opening all the way when cold and holding it? Perhaps just more cleaning? The crap I pulled out of my idle bleed passage today was totally f'd up. I mean how could that much crap end up in an idle bleed?

i've got some thoughts on this now.
and its to do with the retarded ignition on idle that some cars have.
for emissions.
your car may or may not have it.
see photo request above.
its the vac line off the back of the distributor that runs to the vac port on the TB.
thats the port on the TB that faces towards the front of the car.

been doing some reading about problems of cars back in the day.
weak idle at cold start up caused by above.
?????
but who knows.

Vacuum retard makes a nice idle possible...

Never seen an emissions sticker in the engine bay. But the car is dual vacuum and was manufactured 12/73

I never put it in the freezer to see how open it would go. But it seemed to open and close with ease. I spent my day winterizing my boat… which I was a bit late on lol. But maybe I can have some time tomorrow to mess with that a bit.

@Van B

thanks for photos and vin info.

if the emissions sticker is still there its on the lhs side wall of the engine bay,
just above where the relay board and the air cleaner are.

be handy to know what engine code it has written there.
be something like EC-B or EC-A.

any idea where the car might have been originally sold new.
did you get a glovebox manual? would have a dealer stamp maybe.

-

re the retard at idle.
i think you already know about this?

but for emerygt350's interest.

some, but maybe not all 1.8s hook up both sides of the double can vac on the distributor.
the small side is known as a retard can. the larger side is advance.

the small side if it is connected to the throttle body port that is downstream of the throttle plate (engine side) uses engine vacuum at idle to retard the ignition a further 3 degrees or so than 7.5 btdc (or ideal idle). what that does is make the engine reduce NOx emissions at idle. lowers combustion temp. though it also has the effect of raising exhaust temp (Still got to get my head around that bit). at that retard (about 4 deg btdc) you won't get a smooth take off at that level of retard except the minute you snap the throttle open the engine instantly comes off vacuum and the distributor snaps to 7.5 - and you do get smooth take off.
also the engine cranks and fires at 7.5 for ideal starting before it goes into its full emissions retard idle.

emery350gt -its why you time the 1.8 at 7.5 btdc at idle with the hoses off.
you get it to 850+ or -. then you put the hoses back on and do a fine tune on the idle speed after they are back on. some say to block both the hoses, but my logic tells me you only need to block the retard hose. it doesn't hurt to block both. the manual mentions nothing about blocking the hoses at all. so

i've come across some material that says this - while it was good for meeting the idle emissions standards it did cause the engine to run hotter while stuck in traffic. and it was mentioned could cause weak and stumbling warm up idle.

i'm wondering if that is a feature of our cars with both vacuum ports connected to both throttle ports. an easy test would be to pop the vacuum retard hose off the back of the distributor can at start up and see what it does. (you need to pop it off and block it just so you are not pulling any air in the port near the throttle.) basically disable the retard at idle and see if its a steadier faster warm up?

i think vw and porsche might have been doing this themselves right through 74 trying out variations as there seem to be a number of distinct versions with and without both hoses hooked up.

@Van B

yours is the splitting image of the setup on mine.

Click to view attachment

@wonkipop retarding further is just sparking later and sending the exhaust out while it’s still burning.
Also, there’s no mechanical difference between blocking both the advance and retard distributor port or leaving them open to atmosphere. Either way neutralizes them. But blocking does ensure nothing gets in the port. However, I think you would want to block the port on the TB to avoid air leak.

Testing your cold start theory wouldn’t be hard. But it would be time consuming given the need for a cold engine. You would have to start the car, get it warm, pull the retard port, set air screw for correct warm idle, pinch/block line from TB, and confirm timing is correct. Then, stare at the car outside in the cold for several hours while you wait for it to cool down completely*, and start it again to see what happens.

I’ll try it tomorrow and report back.

*or go do something else

Well, emissions sticker is there… its also gone forever. It was sprayed over when new with corrosion protection. So, not likely it would survive any attempt to reveal it.
Engine number is EC008741, but that’s the best I got. Other than it’s a US spec with the low compression pistons that provide a whopping 76hp/91ft lbs… to the crank.

was thinking plugging the hose so it does not leak air into the throttle body.
you pull the lines off the distributor end to take the distributor out of the equation.
as you say the ports don't need the blocking, its the hose. you leave the hose on the throttle body ports.

i think all that would happen is the car will start just fine and theoretically should idle faster. a quick experiment is what i was thinking. then just put the line back on the distributor when finished. the retard is not there at fire up, it starts on 7.5 btdc regardless of hose on or off, vacuum kicks in shortly or immediately there after. so just go out there when its cold, pull the line off the dist. plug it. fire it up and see what happens.

thanks for explanation re hot exhaust. now i get it.

sounds like an owner/dealer that knew about the dreaded battery/hell hole corrosion problem even in 1974 and did some proactive work!?

never mind.

there is one more thing you can look for when you get a moment.
these engines get white stamped numbers on their tin ware.
the number ought to still be there with a bit of luck.
if you look down on lhs side of engine between the air cleaner and the heater fan you might be able to see it. might be either 604 or 605. or it could be some other number.
its down near the snap in cover for the alternator adjustment hole.

there is a chance its on the right hand side of the tin near the battery. but more likely its on the left hand side.

there is one other thing you can look for which is the little white tuning sticker.
usually on tin on top of engine on left hand side. it might not be there any more.
fairly fragile. if it is there take a snap of it and post it up.

thanks for all the info so far. its fairly useful. trying to work out why there was an EC-A engine that had california and 49 states and then there was also an EC-B engine with the same. starbear and i have the EC-B one.
and then there is also an EC-B which had only 49 state. its fairly weird what was going on. we are trying to work out what the differences were. don't think we can ever work out the why!

yeah - the horsepower from these engines is frightening.
i took mine out for a run this morning. hit the streets early before the post lockdown zombies got on the roads. went for a run down by the docks and opened her up.
acceleration almost made my head move but maybe it was the gear changes.
i'm trying out one more theory with mine which is the gas might have gone off.
we have been restricted/locked down here so i've basically had 3/4 of a tank of gas in it for the last 4-5 months i've slowly used (i've lost track of time!) and i am wondering whether the octane has dropped. it can happen.
i will see what a cold start next weekend is like on some topped up fresh gas?

I haven't looked at the availability of the Datsun stuff in a long time. Sorry.

But I do know there were a lot more Datsuns made with L-Jet than 914s. So the wrecking yards should have some of them.

Clay

@Van B if you want/need a new tune up sticker (on the tin to the left of the oil filler neck I made some reproductions. PM me and I’ll mail one to you. ps: my car was produced 11/73 and has a 605 engine tin stamp; wonkipop car produced 1/74 and has a 604 tin stamp. There’s a current thread on this topic too.
@wonkipop if the photos are of your engine looks like your sticker has cracked/flaked. I think I sent you one or two some months ago?

I’m gonna say it says 604. I almost lost what was left by wiping it lol.

Oh and @starbear I would love to have a sticker! Someday soon, I want to restore this engine and make it look all clean and new again

Yep; looks like 604 to me. Consistent with wonki’s.
For the sticker just pm me with your mail address. Will mail you one.

i do have to put that sticker in.

calling all 74 1.8 owners reading this thread.


wonki + starbear are trying to work out some history stuff for mr b (jeff bowlsby).
(because 74 1.8s are the best 914s right? )

if the info is still on your car this is what we need.
cars have to be unmodified and reasonably original (don't have to be in show condition, need to be unmolested).

1. Vin date.
2. engine bay emission sticker (image).
3. engine tune up sticker (image).
4. painted number on engine if its still there (image if you can).
5. distributor vacuum hose set up from dist to throttle body (image).
6. part number on the throttle body if you can read it. (image of TB).

thanks - keep those 1.8s going.

@wonkipop
I did your experiment today and here’s what I found:

-marginally improved kickover
—initial RPMs surged a little higher (900-1000RPM)
—seemed to start quicker
-warmup idle still sluggish (700RPM)
-off idle and low RPM throttle response did improve
—liked the improvement enough I think I will leave it for a while

Also, I have my idle set for 850 RPM

i got the thought from vw porsche themselves.
they had two versions of the 50 state 1.8 floating around in 74.
one of them did not use the retard plumbing on the dist/TB.

did not even know there was that second version until i started doing some digging on a question for mr. b.

don't know the why of it, when the different versions kicked in or anything about it much other than there were two versions. (at least).

far as i can tell the difference was they either introduced or abandoned retarded idle.

i would have thought they needed the retarded idle for california - period.
it had harsher NOx standards in 74 than the 49 states.
but it turns out even that logic does not hold as unretarded idle versions have cali certification. and i have worked out the example in question that demonstrates that is unmolested, unchanged and the way it came. the tune up sticker proved it.



main thing is it worked for you. to some extent.

thats why starbear and i are after that information listed above from owners.
its fairly interesting in the context of L jet and its introduction.
914s and 412s being the first cars anywhere to get it.

By VIN date do you mean production date?

My emission sticker on my (my father's) 74 had some overspray from a trunk hinge repair done before my time. I used isopropyl alcohol on a q-tip to remove the overspray paint and it removed the paint and didn't harm the sticker. I learned the trick from a friend of mine.

Yeah, this is 48yr old ziebart rustproofing… it ain’t coming off.

Ah okay. No worries. I didn't know it was undercoating/rustproofing.

extreme hell hole paranoia - and in 1974! ha.

well both if you can work it out.
the date on the vin sticker.
and if you have your karmann # by all means.


EDIT
its great you got your dad's car.

Alright…. That didn’t work. I guess the car wasn’t really cold when I tried it the other day. But today the car didn’t even try to start and then became instantly flooded. Total shitshow! Theeennnn I realized that even when I tighten the distributor, it can still move enough to alter timing slightly if it’s bumped or nudged.

Oh and the seatbelt interlock started messing up and so I had to fix that before I could continue on setting the car back to the way it was.

Bottom line: leave the hoses on.

ah well
good thing you are the guinea pig before i go in mucking about in a month or so.

---

that fugen seat belt interlock screwed with me 30 years ago.

there was a relay still in the circuit under the passenger seat.
there wasn't one anymore after i got through with it.

@Van B

attached the definitive on how the cold start valve works.
your observation it only opens during cranking 100% right.

Click to view attachment

i found some more from same source regarding AAV being responsible in the main for fast idle warm up. i'm favouring my mechanic's instinct that its the AAR closing too fast in the case of my car for the idle stumble. link to source.

http://www.914world.com/bbs2/index.php?aut...;showentry=2520

I want more air through the Aux Air Valve… as in a bigger valve. I would rather see a cold start idle similar to what I have on my 996. 1500RPM is a good speed to get all the oil circulating and still low enough that you’re not really putting a load on the engine.

i did the cold start test today with the tank top off of fresh gas.
guess what.
no idle stumble phase between minute 2 and 3.
it kind of went down after 2 minutes and was lower for a minute and then came back up and warmed up. but no nearly dying thing.

gas goes off, even after only 3-4 months? enough to upset the old 1.8
a 356 bloke i was talking to recently told me that modern gas drops octane faster than gas even 10 years ago.
we don't have the E gas stuff down here so that is not the cause.
its just modern petrol.

i can blame that bit of the cold stumble on dickhead dan?

I sort of saw that a few years ago but with maybe 6-month old gas, despite having stabilizer added to it. Since then have been using premium 93 octane as I don’t drive it a lot so extra $ not a big issue. Been driving it more this year, too, so gas doesn’t get stale. Helped stop the knock at low driving rpm, too.

I don't really have a process for the 914, but in my 996 I added some race gas on every fill-up. That stuff always has good stabilizers in it and its worth a few extra ponies. One addendum though, you gotta avoid the oxygenated race fuels. I'm talking the old school highest octane you can get for unleaded.

Just did a little test and I figured I would report my findings.

I pulled the AAV out and bridged the tubing from intake boot to plenum. The car fired up instantly from completely cold and jumped to 1500RPM!
Things were looking promising but just a few seconds later I started to get what looked like a runaway situation. The revs climbed up to 3500RPM so, I put my hand over the intake snorkel to choke it down. I let it fall to <1000RPM and then uncovered. The revs then climbed back up to 1500-1600RPM and stayed there.
However, I did notice the engine was rich and I could make out a little black smoke amongst the condensation from the exhaust.
I gave the throttle a rev to clear it out and then killed it.

As a result, I have yet again inspected the AAV, but can’t see anything wrong. Movement is free, spring tension is consistent, and it is totally clean.

So, the only thing I could see is that when I pulled it from the car, while still cold, it wasn’t quite fully open, but was close. The opening is not real large even at full opening, but that last little bit could be considered the most important since it’s part of the full ellipse shape and not the triangular (closing) side.
I’m going to leave it in the freezer for a couple hours and see what it looks like then.

My thoughts from this little experiment are that full pipe diameter is too much so, the restrictive shape of the AAV makes more sense to me now. But, and this is my hypothesis, if the spring has fatigued, I’m not going to get max flow through the valve.

Further, somewhere less than full tube size and current AAV aperture I’m getting now should be a proper high idle.

I guess I’ll see what I learn from the freezer.

Van

Onward!

great experiment mate

i can remember mine 30 years ago as a 15 year old car. and it started up and idled fast.
maybe not 1500, but i seem to remember around 1200. could be a faulty memory, its a long time ago. but it def. started at a faster idle and came down.

looks like the AAV is a very finely tuned thing and it does not take much to get out of synch and not be just right?

as to gas. we can get three grades here. 91, 95 and 98. i've been running 95.
i might start using 98. might keep it fresh for longer. the 356 man said he had really noticed the gas going off faster for the last 5 years or so. similar problem, doesn't drive his car enough.

mine runs rich during that first warm up phase. same as yours. can see it in the exhaust and even what is being spat out in the moisture. the mechanic who helps out and looks after things no doubt observed that. probably why he was pretty sure i was the AAV? means the ECU and sensors 1 and 2 are still working close to correctly and its enriching the mixture.

We use RON+MON/2 here in the states. That’s why our octane numbers are lower. Motor Octane is a much lower figure than Research Octane so, it drags the average down.

Just a short update for the record:
I had noticed that on the two times I’ve driven the car at night, it would almost refuse to idle until completely warmed up. So, on a hunch, I thought maybe the voltage regulator was causing some faulty signals. There are definitely classic symptoms like dim lights at idle etc. So, after screwing up and buying a cheap replacement that didn’t fit, I spend $200 on a Bosch solid state.
Started did a cold start as soon as I installed it, no change. Man this thing struggles when cold…

I’m starting to get frustrated. And doubly so that there’s no L-Jet expertise around here. I suppose I’ll just throw parts at it for a while and see what happens. Nothing is broken so, I’m thinking there’s a possibility it could be a collection of parts that aren’t working properly.

had that very chat today over lunch with mike.
he still says its the AAV and its degradation is in combination with the retarded idle. early smog stuff.
its a crude device compared to modern cars.

he had an interesting suggestion to me which was try a cold start with the aav unplugged (electrical connection) and see what it does. eventually it closes due to engine heat but that will stop the electrical coil heating and closing it. this was not as a solution, but just to see if maybe he was right.

i might try it as an experiment.

now that its warmer here (real hot today) mine is starting and warming up quickly. but not with a faster idle. the aav is effectively a choke. and i remember the auto chokes on twin carb vws were pretty much on the blink and uneven side to side after a mere 10 years. i had them unplugged back in the day and just used to sit there and warm it up until it would idle rather than deal with auto chokes. i had them wound off.

--------

i was getting the low down from mike on why vw would have disconnected vacuum advance for california. his view was it was another crude way to meet californian emissions by always slightly retarding the engine at cruise and as you came off throttle.
a trick to burn just enough hydrocarbons in the exhaust and not make too much NOx to pass the lab smog test. "crude" because they were adapting the behaviour of the double can distributor that was more ideal for the 49 state cars. ie cheap.